Taking one last look at 2011’s fifth annual Electric Aircraft Symposium, your editor regrets the fits and starts in its coverage. Next week, we’ll begin looking at the extraordinary presentations from this year’s gathering. Huw W. Hampton-Jones from Oxis Energy, a British company developing a Lithium Sulfur battery, claimed his firm’s “technology is based around the use of Lithium Sulphur to produce batteries which are superior in terms of energy, weight, cycle life, costs, ageing and safety.” Lithium sulfur is well known in military circles for providing primary (non-rechargeable) power to field operations. Perlan I flew with SAFT 5590 primary batteries, partly because of their superior energy density compared to lithium-ion cells, and partly because of their greater resistance to thermal runaways, or self-igniting fires sometimes seen in lithium batteries. Weight was a significant concern on this high-altitude craft. When working on the fringes of the battery selection effort for Perlan II, headed by Einar Enevoldson, James Murray and Eric …
Green Flight Challenge – Days Three and Five
As if in answer to the most fervent prayers by CAFE Foundation organizers, Tuesday, September 27 dawned as a bright, windless morning, perfect for the planned 200 -mile aerial trek that each of four teams would undertake in the Green Flight Challenge sponsored by Google. Each would fly a large, tightly-followed out-and-return loop around the Sonoma Valley, reaching the radio tower array on the peaks north of Geyserville, then returning for one of three passes (the fourth being the descent to land) over the CAFE Foundation hangar at the west end of the Charles M. Schulz Sonoma County Airport. Each would have to reach at least 4,000 feet at the end of a 17-mile climb and would need to track within one mile on either side of the Challenge course’s centerline. Pilots would need to stay on the outside edge of turnpoints, but shave their margin to within one-half mile on each pylon-type turn. To help monitor that precise flying, Steve …